The invention relates to a method and an apparatus for the production of mailing bags, including envelopes, from material in web form which is processed in numerous ways with the aid of a plurality of method steps and, accordingly, in a plurality of workstations.
For the above purpose, the material in web form is trimmed at its edges and cut through, provided with adhesive, folded and bonded. In special cases, a second, flat part such as, for example, a cut-to-size window piece, a sticker, an adhesive-masking strip or another, additional part forming the mailing bag or the envelope blank is additionally fixed with the aid of adhesive directly to the material in web form or to a cut-to-size piece or blank. The technical effort involved therewith is great and, in particular, causes a problem when the aim is significantly to increase the number of mailing bags or envelopes to be produced per unit of time.
It is therefore an object of the invention to indicate method steps and the associated apparatus whereby it is possible to increase the number of units per unit of time in the production of mailing bags, including envelopes, which consist not merely of one part but of at least two, initially separate parts.
In order to achieve the stated object, the invention provides a method of producing mailing bags from two parts that are joined to each other with an adhesive in a joining station, wherein at least one of the parts is provided with the adhesive, and then the two parts are placed in contact with one another during an arcuate movement thereof. Especially according to the invention, at least one of the two parts and/or its carrier performs an undulating movement in the region of the junction station. The actual contact and junction station is only minimally larger than a linear contact surface. Its curvature and position are predetermined by the curvature of the suction roller serving as an applicator roller. Immediately adjoining the actual contact station, the curvature of at least one of the two parts and/or its carrier is directed counter to the curvature of the applicator roller and then makes an immediate transition into a preferably common plane. The respective arcuate pieces are extremely short.
The guidance and handling of the two parts during superposition and bonding is, in the stated manner, simpler than previously, in particular because virtually no belt tensions caused by the curvature arise and also because, as a rule, only one of the two parts to be joined to one another has to be bent to conform to the curvature of the applicator roller. At least one of the two parts therefore runs in a virtually linear manner through the contact and junction station and is nevertheless guided with minimum undulation. The consequence of this is that larger numbers of units than previously can be achieved per unit of time.
For the performance of the method according to the invention, provision is further made for at least one of the two parts and/or its carrier, at the junction station, initially to move convexly into a trough and then concavely through the trough and finally convexly again out of the trough. The respective arcuate pieces are extremely short and therefore cause not a pronounced but only a minimal curvature. In order to achieve this, the trough according to the invention is only shallow and may possess a maximum depth of, for example, 1.5 mm to 2 mm.